Reinforced polyamide molding compounds having low haze and molded bodies therefrom

Abstract

The present invention relates to a polyamide molding compound comprising the following components or consisting of these components: (A) 40 to 95 wt % of a specific polyamide mixture consisting of the polyamides (A1) and (A2); (B) 5 to 50 wt % of at least one glass filler having a refractive index in the range from 1.540 to 1.600; (C) 0 to 10 wt % of at least one additive; wherein the weight proportions of the components (A) to (C) add up to 100% wt %; wherein the at least one transparent polyamide (A2) has a transparency of at least 90% and a haze of at most 3%. The present invention additionally relates to molded bodies composed of this polyamide molding compound.

Claims

1. A polyamide molding compound comprising the following components: (A) 40 to 95 wt % of a polyamide mixture consisting of the polyamides (A1) and (A2), wherein (A1) 42 to 68 wt % of at least one semi-crystalline polyamide is selected from the group comprising PA 46, PA 66, PA 66/6, PA 610, PA 612, PA 614, PA 615, PA 616, and mixtures thereof; and (A2) 32-58 wt % of at least one transparent semi-aromatic polyamide having at least 30 mol % of monomers having aromatic structural units, with respect to the total quantity of diamines and dicarboxylic acids is in the polyamide (A2) that is amorphous or microcrystalline; (B) 5 to 50 wt % of at least one glass filler having a refractive index in the range from 1.540 to 1.600; and (C) 0 to 10 wt % of at least one additive; wherein the weight proportions of the components (A) to (C) add up to 100% by weight of the component (A) and the weight proportions of the components (A1) and (A2) add up to 100% by weight of component (A); wherein the polyamide molding compound has a transparency of at least 80% and a haze of at most 40%; wherein the transparency and haze of the polyamide molding compound are measured in accordance with ASTM D1003 on a molded plate of the polyamide molding compound having a dimension of 60 mm60 mm2 mm.

2. The polyamide molding compound in accordance with claim 1, wherein the polyamide mixture (A) comprises 45 to 65 wt % polyamide (A1); and 35 to 55 wt % polyamide (A2); and/or the proportion of component (A) in the polyamide molding compound is in the range from 49 to 90 wt % with respect to the sum of components (A) to (C); and/or the proportion of component (B) in the polyamide molding compound is in the range from 10 to 45 wt % with respect to the sum of the components (A) to (C); and/or the proportion of component (C) in the molding compound is in the range from 0 to 6 wt % with respect to the sum of components (A) to (C).

3. The polyamide molding compound in accordance with claim 1, wherein the polyamide (A1) is PA 66.

4. The polyamide molding compound in accordance with claim 1, wherein the at least one transparent polyamide (A2) comprises at least 35 mol % of monomers having aromatic structural units, with respect to the total quantity of diamines and dicarboxylic acids.

5. The polyamide molding compound in accordance with claim 1, wherein the monomers having aromatic structural units for the transparent polyamide (A2) are selected from the group consisting of terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid (NDA), biphenyldicarboxylic acid, 4,4-diphenyl ether dicarboxylic acid, 4,4-diphenylmethanedicarboxylic acid, and 4,4-diphenylsulfonedicarboxylic acid, 1,5-anthracene dicarboxylic acid, p-terphenylene-4,4-dicarboxylic acid, 2,5-pyridine dicarboxylic acid, xylylenediamine, and mixtures thereof.

6. The polyamide molding compound in accordance with claim 1, wherein the transparent polyamides (A2) are made up of the following monomers: (a-A2) 0 to 100 mol % of cycloaliphatic diamines, with respect to the total quantity of diamines; (b-A2) 0 to 100 mol % of diamines having aromatic structural units, with respect to the total quantity of diamines; (cA-2) 0 to 100 mol % of open-chain, aliphatic diamines, preferably having 6 to 10 carbon atoms, in particular having 6 carbon atoms, with respect to the total quantity of diamines; (d-A2) 0 to 70 mol % of open-chain aliphatic dicarboxylic acids, with respect to the total quantity of dicarboxylic acids; (e-A2) 30 to 100 mol % of aromatic dicarboxylic acids, with respect to the total quantity of dicarboxylic acids; (f-A2) 0 to 70 mol % of cycloaliphatic dicarboxylic acids, with respect to the total quantity of dicarboxylic acids; and (g-A2) 0 to 40 wt % of lactams and/or aminocarboxylic acids having 6 to 12 carbon atoms, with respect to the total quantity of the monomers (a-A2) to (g-A2), where the sum of the diamines (a-A2), (b-A2), and (c-A2) produces 100 mol %; where the sum of the dicarboxylic acids (d-A2), (e-A2), and (f-A2) produces 100 mol %; and where the sum of the monomers (b-A2) and (e-A2) amounts to at least 30 mol %, with respect to the sum of the total diamines and of the total dicarboxylic acids in the polyamide (A2).

7. The polyamide molding compound in accordance with claim 6, wherein the cycloaliphatic diamine (a-A2) is selected from the group consisting of bis(4-amino-3-methylcyclohexyl)methane, bis-(4-aminocylcohexyl)methane, bis-(4-amino-3-ethylcyclohexyl)methane, bis-(4-amino-3,5,-dimethylcyclohexyl)methane, 2,6-norbornane diamine, 1,3-diaminocyclohexane, 1,4-diaminocyclohexanediamine, isophorone diamine, 1,3-bis-(aminomethyl)cyclohexane, 1,4-bis-(aminomethyl)cyclohexane, 2,2-(4,4-diaminodicyclohexyl)propane, and mixtures thereof; the aromatic diamine (b-A2) is selected from xylylenediamines; and/or the diamine (c-A2) is selected from the group consisting of 1,4-butanediamine, 1,5-pentanediamine, 2-methyl-1,5,pentanediamine, hexanediamines, 2,2,4-trimethyl-1,6-hexamethylenediamine, 2,4,4-trimethyl-1,6-hexamethylenediamine, nonanediamines, 1,10-decanediamine, 1,11-undecanediamine, 1,12-dodecanediamine, 1,13-tridecanediamine, 1,14-tetradecanediamine, 1,18-octadecanediamine, and mixtures thereof; and/or the aliphatic dicarboxylic acid (d-A2) is selected from the group consisting of 1,6-apidic acid, 1,9-nonanedioic acid, 1,10-decanedioic acid, 1,11-undecanedioic acid, 1,12 dedecanedioic acid 1,13-tricanedioic acid, 1,14-tetradecanedioic acid, 1,16-hexxdecanedioic acid, 1,18-octadecanedioic acid, and mixtures thereof; and/or the aromatic dicarboxylic acid (e-A2) is selected from the group consisting of terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid (NDA), biphenyldicarboxylic acid, 4,4-diphenyl ether dicarboxylic acid, 4,4-diphenylmethanedicarboxylic acid, and 4,4-diphenylsulfonedicarboxylic acid, anthracene dicarboxylic acid, p-terphenylene-4,4-dicarboxylic acid, and 2,5-pyridinedicarboxylic acid, and mixtures thereof; and/or the cycloaliphatic dicarboxylic acid (f-A2) is selected from the group consisting of 1,3-cyclopentanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 2,3-norbornanedicarboxylic acid, 2,6-norbornanedicarboxylic acid, and mixtures thereof; and/or the lactam and/or the ,-aminocarboxylic acids (g-A1) and/or (g-A2) is/are selected from the group consisting of m-aminobenzoic acid, p-aminobenzoic acid, caprolactam (CL), ,-aminocaproic acid, ,-aminoheptanoic acid, ,-aminooctanoic acid, ,-aminononanoic acid, ,-aminodecanoic acid, ,-aminoundecanoic acid (AUA), laurolactam (LL), and ,-aminododecanoic acid (ADA).

8. The polyamide molding compound in accordance with claim 1, wherein the transparency of the polyamide molding compound amounts to at least 83%; and/or the haze of the polyamide molding compound amounts to a maximum of 35%, or wherein the molded body has an arithmetical mean roughness Ra determined in accordance with DIN EN ISO 4287 (2010-07) by means of a MarSurf XR1 Surface Measuring Station of at most 0.12 m and/or has a surface roughness R.sub.z of at most 1.50 m.

9. The polyamide molding compound in accordance with claim 1, wherein the polyamide (A2) is selected from the group consisting of PA 6I/6T, PA 10I/10T, PA DI/DT (D=2-methyl-1,5-pentanediamine), PA MACMI/12, PA MACMI/1012, PA MACMT/12, PA MACMI/MACMT/12, PA MACMI/MACMT, PA MACMI/MACMT/MACM12, PA 6I/6T/MACMI/MACMT, PA 6I/6T/MACMI/MACMT/12, PA 6I/MACMI, PA 6I/6T/PACMI/PACMT, PA 6I/612/MACMI/MACM12, PA 6T/612/MACMT/MACM12, PA 6I/6T/612/MACMI/MACMT/MACM12, PA 6I/6T/MACMI/MACMT/PACMI/PACMT, PA 6I/6T/MACMI/MACMT/PACMI/PACMT/12, PA MACMI/MACMT/MACM36, PA MACMI/MACM36, PA MACMT/MACM36, PA 12/PACMI, PA 12/MACMT, PA 6/PACMT, PA 6/PACMI, PA MXDI, PA MXDI/MXD6, PA MXDI/MXD10, PA MXDI/MXDT, PA MXDI/MACMI, PA MXDI/MXDT/MACMI/MACMT, PA 6I/6T/BACI/BACT, PA MACMI/MACMT/BACI/BACT, PA 6I/6T/MACMI/MACMT/BACI/BACT, and mixtures thereof.

10. The polyamide molding compound in accordance with claim 1, wherein the at least one glass filler (B) is selected from the group consisting of glass fibers, ground glass fibers, glass particles, glass flakes, glass spheres, hollow glass spheres, and combinations thereof.

11. The polyamide molding compound in accordance with claim 1, wherein the glass type of the at least one glass filler (B) is selected from the group consisting of E-glass, E-CR-glass, R-glass, AR-glass, and mixtures of glass having substantially the same refractive index.

12. The polyamide molding compound in accordance with claim 1, wherein the at least one additive (C) is selected from the group consisting of inorganic and organic stabilizers, monomers, impact modifiers, lubricants, colorants, marking means, photochromic agents, demolding means, condensation catalysts, chain regulators, foaming agents, anti-blocking agents, optical brighteners, non-halogen flame retardants, natural sheet silicates, synthetic sheet silicates, nanoscale fillers having a particle size (d90) of a maximum of 100 nm, and mixtures thereof.

13. The polyamide molding compound in accordance with claim 1, wherein component (A2) has a glass transition temperature determined in accordance with ISO 11357-2 of at least 120 C.

14. A molded body comprising a polyamide molding compound in accordance with claim 1.

15. The molded body in accordance with claim 14, which is a multilayer molded body.

16. The polyamide molding compound in accordance with claim 5, wherein the monomers having aromatic structural units for the transparent polyamide (A2) are selected from the group of terephthalic acid, isophthalic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and mixtures thereof.

17. The polyamide molding compound in accordance with claim 5, wherein the monomers having aromatic structural units for the transparent polyamide (A2) are selected from the group of terephthalic acid, isophthalic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, meta-xylylenediamine, and mixtures thereof.

Description

1 Measurement Methods

(1) The following measurement methods were used within the framework of this application:

(2) Surface Roughness, R.sub.a, R.sub.z

(3) The roughness of the test specimens was measured in accordance with DIN EN ISO 4287 (2010-07) using a MarSurf XR1 Surface Measuring Station of Mahr GmbH (DE). The roughness values, that is, the arithmetical mean roughness Ra and the surface roughness R.sub.z, are given in micrometers (m).

(4) Haze, Transparency

(5) The transparency and haze were measured in accordance with ASTM D1003 on a measuring device Haze Gard Plus of BYK Garder at plates of 2 mm thickness (60 mm60 mm surface) with CIE light type C at 23 C. The surface of the specimen (plate 60602 mm) had an arithmetical mean roughness R.sub.a and a surface roughness R.sub.z as explicitly specified for the molding compounds in accordance with the examples and comparison examples in Table 2 or for the multilayer molded body. The manufacture of the test specimens will be described under item 3.3.

(6) Melting Point (T.sub.m) and Enthalpy of Fusion (H.sub.m)

(7) The melting point and the enthalpy of fusion were determined in accordance with ISO 11357-3 (2013) on pellets. The DSC (differential scanning calorimetry) measurements were performed at a heating rate of 20 K/min.

(8) Glass Transition Temperature, T.sub.g

(9) The determination of the glass transition temperature T.sub.g took place in accordance with ISO 11357-2 (2013) at pellets by means of differential scanning calorimetry (DSC). It was performed in each of the two heating steps at a heating rate of 20 K/min. The sample was quenched in dry ice after the first heating. The glass transition temperature (T.sub.g) was determined in the second heating step. The center of the glass transition zone, that was here specified as the glass transition temperature, was determined using the half height method.

(10) Relative Viscosity, n.sub.Rel

(11) The relative viscosity was determined in accordance with ISO 307 (2007) at 20 C. 0.5 g polymer pellets were weighed into 100 ml m-cresol for this purpose; the calculation of the relative viscosity (RV) after RV=t/t.sub.0 took place on the basis of the section 11 of the standard.

(12) Modulus of Elasticity

(13) The determination of the modulus of elasticity and of the tensile strength was carried out in accordance with ISO 527 (2012) at 23 C. at a tensile speed of 1 mm/min at an ISO tensile rod (type A1, mass 17020/104) manufactured in accordance with the standard: ISO/CD 3167 (2003).

(14) Failure Stress and Elongation at Break

(15) The determination of the failure stress and of the elongation at break was carried out in accordance with ISO 527 (2012) at 23 C. at a tensile speed of 5 mm/min at an ISO tensile rod, type A1 (mass 17020/104) manufactured in accordance with the standard ISO/CD 3167 (2003).

(16) Impact Resistance According to Charpy

(17) The determination of the impact resistance according to Charpy was carried out in accordance with ISO 179/2*eU (1997, *2=instrumented) at 23 C. at an ISO test rod, Type B1 (mass 80104 mm), manufactured in accordance with the standard ISO/CD 3167 (2003).

(18) Notch Impact Resistance According to Charpy

(19) The determination of the notch impact resistance according to Charpy was carried out in accordance with ISO 179/2*eA (1997, *2=instrumented) at 23 C. at an ISO test rod, Type B1 (mass 80104 mm), manufactured in accordance with the standard ISO/CD 3167 (2003).

(20) Heat Deflection Temperature (HDT)

(21) The heat deflection temperature (HDT) or also deformation temperature under load is reported as HDT/A and/or HDT/B. HDT/A corresponds to method A having a bending stress of 1.80 MPa and HDT/B corresponds to method B having a bending stress of 0.45 MPa. The HDT values were determined in accordance with ISO 75 (2013-04) at ISO baffle rods with the dimensions 80104 mm.

(22) Measuring the Refractive Index of Glass Fibers

(23) The determination of the refractive index of glass fibers and of polyamide (A1) took place using the Beck's line method and using immersion fluids with respect to 589 nm based on method B of ISO 489 (1999-04).

(24) Measuring the Refractive Index of Polyamides

(25) The refractive index of the polyamide (A2) was determined in accordance with ISO 489 (1999-04) at plates of 2 mm thickness (60602 mm) at a wavelength of 589 nm and at a temperature of 23 C. by means of an Abbe refractometer of Carl Zeiss (method A). 1-1-bromonaphthalene was applied as the contact fluid between the examined plate and the prism surface.

2 Starting Materials

(26) The materials used in the examples and in the comparison examples are collated in Table 1.

(27) TABLE-US-00001 TABLE 1 Materials used in the examples and in the comparison examples Components Description Manufacturer PA66 PA 66 (Radipol A45) RadiciGroup Component (A1) Rel. viscosity = 1.85 Refractive index: 1.5360 Transparency: 59%; Haze: 100%; Tm: 260 C. Polyamide 1 PA 6I/MACMI/6T/MACMT (77/13/8/2) EMS-CHEMIE AG Component (A2) Rel. viscosity = 1.42 (Switzerland) Aromatic structural units: 50 Mol-% Refractive index: 1.582 Transparency: 93%; Haze: 0.5%; Tg: 147 C. Polyamide 2 PA 6I/6T/MACMI/MACMT/PACMI/PACMT/12 EMS-CHEMIE AG Component (A2) (39/39/7.1/7.1/2.5/2.5/2.8) (Switzerland) Rel. viscosity = 1.62 Aromatic structural units: 50 Mol-% Refractive index: 1.583 Transparency: 93%; Haze: 0.5%; Tg: 159 C. Polyamide 3 PA 6I/6T) (67/33) EMS-CHEMIE AG Component (A2) Rel. viscosity = 1.54 (Switzerland) Aromatic structural units: 50 Mol-% Refractive index: 1.591 Transparency: 93%; Haze: 0.6%; Tg: 125 C. Glass fiber 1 OC Micromax 771 Owens Corning Refractive index: 1.556 Glass fiber 2 ECS 301T-3 CPIC (China) Refractive index: 1.556

3 Examples and Comparison Examples

(28) 3.1 Manufacturing the Polyamide Molding Compounds

(29) The components are generally mixed (compounded) on standard compounding machines such as single-shaft or twin-shaft extruders or screw kneaders in the polymer melt to manufacture the plastic molding compound. The components are here individually metered into the feeder or are supplied in the form of a dry blend. If additives are used, they can be introduced directly or in the form of a master batch. In a dry blend manufacture, the dried polymer pellets and the additives are mixed. The mixing can take place under a dried protective gas to avoid moisture absorption. The glass fibers used are metered into the polymer melt in the intended ratio via a side feeder and are further homogenized in the cylinder of the compounding machine. The metering of all the components into the feeder or side feeder is set via electronically controlled scales such that the desired quantity ratios of glass-polymer result therefrom.

(30) The compounding takes place at set extruder cylinder temperatures of e.g. 230 C. to 350 C. Vacuum can be applied or atmospheric degassing can take place in front of the nozzle. The melt is output into a water bath in extruded form and is pelletized. An underwater pelletization or a strand pelletization is preferably used for pelletization.

(31) The plastic molding compound thus preferably obtained in pellet form is subsequently dried and can then be further processed to molded bodies by injection molding. This takes place via a repeat melting of the dry pellets in a heatable cylinder and conveying the melt into an injection mold in which the melt can solidify.

(32) 3.2 Manufacture of the Polyamide Molding Compound in Accordance with Examples B1 to B4 and VB1 to VB3

(33) The molding compounds for the examples B1 to B4 and for the comparison examples VB1 to VB3 were manufactured on a twin shaft extruder of the company Werner and Pfleiderer, Type ZSK25. The polyamides (A1) and (A2) were metered into the feed of the extruder via metering trolleys in the quantity portions specified in Table 2. The glass fibers used were conveyed into the polymer melt in the intended ratio via a side feeder and were further homogenized in the cylinder of the compounding machine.

(34) The temperature of the first housing was set to 80 C.; that of the remaining housings in an increasing manner from 270 to 300 C. A speed of 200 r.p.m. and a throughput of 12 kg/h were used and degassing took place in the third zone in front of the nozzle in the nitrogen stream. The polyamide molding compound output as a strand was cooled in a water bath, pelletized, and the obtained pellets were dried at 80 C. in vacuum at 30 mbar to a water content of below 0.1 wt %.

(35) 3.3 Manufacture of the Test Specimens

(36) Tensile rods, baffle rods, and plates were injected from the pellets obtained as test specimens at which the properties specified in Table 2 were determined. The test specimens were manufactured on an injection molding machine of Arburg, model Allrounder 420 C 1000-250. Increasing cylinder temperatures from 270 C. to 300 C. were used here. The melt temperature for all the injected molded bodies amounted to 295-305 C. in each to case. The tool temperature was at 120 C. in each case in the case of plates (2 mm60 mm60 mm). The tool temperatures of the tensile rods and of the baffle rods were 80 C. in each case. The test specimens were used in the dry state if not otherwise specified; for this purpose, they were stored for at least 48 h at room temperature after the injection molding in a dry environment, i.e. over silica gel.

(37) In the case of plates (2 mm60 mm60 mm) for determining the optical properties, the surfaces of the cavity of the injection mold were given a mirror finish so that the molded bodies (plates) had a high gloss surface having an arithmetical mean roughness Ra of 0.01 to 0.08 m and/or a surface roughness Rz of 0.05 to 1.0 m, in accordance with DIN EN ISO 4287.

(38) 3.4 Results

(39) TABLE-US-00002 TABLE 2 Examples and comparison examples. Unit B1 B2 B3 B4 VB1 VB2 VB3 Components PA 66 Wt % 44 36 25 40 Component (A1) Proportion of (A1) in Wt % 55 45 50 50 (A) Polyamide 1 Wt % 44 Component (A2) Polyamide 2 Wt % 36 80 Component (A2) Polyamide 3 Wt % 25 40 80 50 Component (A2) Proportion of (A2) in Wt % 45 55 50 50 (A) Glass fiber 1 Wt % 20 Glass fiber 2 Wt % 20 20 50 20 20 50 Properties Haze of the molding % 13 13 33 15 91 97 100 compound Transparency of the % 85 88 83 91 86 81 79 molding compound Ra m 0.065 0.068 0.089 0.061 0.059 0.063 0.088 Plate 60 60 2 mm Rz m 0.845 0.882 0.957 0.788 0.790 0.824 0.974 Plate 60 60 2 mm Modulus of elasticity MPa 7210 7340 17120 7360 6160 7740 16900 Failure stress MPa 170 160 257 163 128 138 248 Elongation at break % 3.2 2.7 2.4 3.7 3.0 2.4 1.8 Impact resistance kJ/mm.sup.2 49 37 85 73 37 35 58 Notch impact kJ/mm.sup.2 9.6 9.4 12 6.9 8.6 8.6 10 resistance HDT A C. 221 223 252 224 148 114 117 HDT B C. 225 227 258 229 153 120 122

(40) Manufacture of the Multilayer Molded Bodies

(41) The following multilayer molded bodies of the dimension 60602 mm were manufactured by back injection molding of films of non-reinforced, transparent polyamide using the polyamide molding compound in accordance with the invention. The manufacture took place on an injection molding machine of Arburg 420C 1000-250 using the conditions described above for the 60602 mm plates. Two extruded films composed of the polyamide 2 (PA 6I/6T/MACMI/MACMT/PACMI/PACMT/12; component (A2)) each having a thickness of 100 m were cut to the size 60600.1 mm, were placed into the injection molding tool, and the remaining cavity between the two films after the closing of the tool was filled by injection the polyamide molding compound in accordance with the invention from example B1. After cooling, the multilayer molded body was demolded and the transparency and haze were determined in accordance with ASTM D1003. The insertion films of polyamide 2 were no longer able to be removed from the multilayer molded body after the injection molding process, but are rather connected with material continuity to the molding compound from the examples B1.

(42) TABLE-US-00003 Multilayer molded body 1 Film of polyamide 2 (t) Design of the External Molding compound multilayer molded body Central of example B1 of the dimension 60 60 2 mm Internal Film of polyamide 2 (b) Transparency % 89 Haze % 11 Ra (t/b) (plate 60 60 2 mm) m 0.026/0.027 Rz (t/b) (plate 60 60 2 mm) m 0.314/0.355

4 Discussion of the Results

(43) It can be seen from Table 2 that the polyamide molding compounds in accordance with the invention in accordance with examples B1, B2, and B4 have a very low haze of 13 to 15% and a high transparency of 85 to 91%. Even the polyamide molding compound filled with 50 wt % glass fiber in accordance with B3 still demonstrates a haze of 33% and a transmission of 83.

(44) The polyamide molding compounds in accordance with the comparison examples VB1 and VB2 in contrast demonstrate a much higher haze of 91% or 97% despite a proportion of glass fiber of only 20 wt %. The comparison of the molding compound with that in accordance with VB3 illustrates a significantly better haze is also obtained for every high proportions of glass filler, here of 50 wt %.

(45) The comparison of the examples B1 to B4 in accordance with the invention with the comparison examples VB1 and VB2, that each only comprise one polyamide (A2), illustrates that a mixture of the polyamides (A1) and (A2) is absolutely necessary to achieve good haze values.

(46) Providing polyamide molding compounds reinforced with a glass filler that also have very good optical properties, in particular low haze, in addition to good mechanical properties is therefore surprisingly only successful by the specific feature combination of the invention as described herein.